Vapor generator



1 Oct. 25, 1938. IRSHWG 2,133,979

VAPOR GENERATOR Filed April 13, 1955 2 Sheets-Sheet l INVENTQR. 17. fit

M'ZZzzm ATTORNEY.

Oct. 25, 1938. w. M. FIRSHING 2,133,979

I VAPOR GENERATOR Filed April 15, 1935 2 Sheets-Sheet 2 M'ZZzhm Milk/25:27.

ATTORNEY.

Pecan on. 25,1938 t 2,133,979

VAPOR GENERATOR William M. Firshing, West New Brighton, Staten Island,lN. Y., assignor to The Babcock & Wil-v cox Company, Newark, N. ,J., a corporation ,of New Jersey Application April 13, 1935; Serial No. 16,123

' 3 Claims. (oi. 1225-327X.

This invention relates to boilers and more dicated. Each of the lower water drums "and particularly to water tube boilers of the type l llisconnected to the upper steam, and water embodying a steam and water drum disposed drum it by a separate set of steam generating above the furnace chamber and connected by 'tubes IS; The hot gases resulting from combus- 5 sets of. downwardly extending tubes with two tion of the-fuel in the chamber I ll rise fromthe 5 water drums, one on each side'of the combustion latter and divide, one part flowing. to the right chamber, the arrangement being such that the and traversing one of the sets of tubes I5 and gases from the furnace chamber pass divergently the other part flowing to the left andtr'aversing right and left through the respective sets of the other set of tubes. In traversing the sets of water tubes to a suitable uptake or uptakes. tubes IS the major portion of the heat therefroml0 The objects of my invention are comprised in is given up to the water within the tubes. The the provision of a water tube boiler of the above gases pass out of the furnace chamber through type which is highly compact, one which is light suitablegas outlets l6 and 11 respectively; in weight for a'given capacity, one which is so The boiler shown in the accompanyingtdraw- 15 designed as to make possible a maximum. of ings is particularly useful in marine applications, combustion chamber space, one which is of a a d, 0 t s d, i8v S pp -fi its bettemlby strong and durable construction, and lastly, one suita le'stru tura m s w h supp t which is highly efliclent in operation. I the water drums l3 and- I through saddles 19 These and other bjects re effected by my inand 20 respectively, secured to the water drums. 20 vention, as will be apparent from an examination e ppe Steam and Water drum i2 is pported 20 of the following description and claims, taken in f e We Water drums l3 and N y t Y connection with the accompanying drawings, in two sets of tubes ii;- In marine installations it UNITED l STATES PATENT OFFICE which: I isrparticularlydesirable to support the boilers Fig. 1 is a transverse, vertical, sectional view from th -ii as headroom i5 ate premium and through a boiler constructed-in accordance with as the shipframes arein the bottom. 25 the present invention; -As will be ,observed from an examination :of

Fig. 2 is an enlarged fragmentary sectional view Fi I ve wn e h Set Of Steam ner tin illustrating the detail arrangement of a portion tube-S as being divided n e pl l ty f of a set of steam generating tubes, the view being ups, t r being three ups t ach set the taken on the line 2-2 of Fig. 1; and a groups being indicated by the reference numerals 30 Fig. 3 is'a view similar to Fig. 1 and illustrates 22 and 3 respectivelya modifiedform of my invention, r In order to provide the necessary strength for It will b recognized as the description prosupporting the .upper steam :and water drum i2 ceeds that my improvement is especially applicafrom the lower Water drums l3 and he group I ble toiboilers used for the generation of steam II h ch ar a a the combustion chamberv 35 on shipboard; however, itis tobe'understood that ere made "Straight for P ic ly their entire in so far as certain of the broader aspects of my n t e t for t i terminalp rtions 24 invention are concerned, my, improved form of thereof, which are Curved t0 l de'radial enwater tube boiler may be used for the generation trances into their respective drums 80 as toas- 40 of steam wherever d, sure good tube seats and the desired character- Referring now in detail to the construction ilistics of lightnessend t en th in the drums and 1 t t d and particularly t t mgdjfication ease of manufacture. The furnace volume is the shown in Figs. 1 and 2 of the drawings, th largest possible consistent withthe strength dereference r l in i d t combustion rived from the straight tubesand contributes to chamber wherein a suitable fuel, for example, light w t fora iv n st ami apa ty y 4 oil is burned. The burners for projecting theoil P i in l e q antities of fuel to be burned and combustion supporting nt t chamber per unit of tube surface with a strong structure. In are indicated 'at H as extending through an tubes forming the groups 2 are similarly end l of t ha b bowed away from the combustion chamber to My improved boiler comprises an upper steam permit expansion and contraction thereof due 5n and water drum vl2 disposed ab th to temperature changes and also'forthe purpose combustion chamber l0 and a pair of lower of Providing the maximum ea flbs bing surwater drums i3 and. I 4 extending in thesame face, the curved tubes being longer than. the general direction as the drum l2 and arranged at straight tubes. The tubes forming the groups 23 opposite sides of the combustion chamber, as inat the outside of the sets of tubes are also simi- 55 toward the combustion chamber.

" sarily present, but not ordinarily used in the conlarly bowed away fromthe combustion chamber for the same reasonas just explained in connection with the groups 22.

With the improved design of the three drum boiler'furnace shown, it is possible to providean.

8% larger combustion chamber space, to burn a correspondingly greater amount of fuel, and to ventional boiler. Hence, my improved boiler furnace does not require anymore room in the ship than the conventional construction, just referred to, yet my furnace is capable of burning more fuel and .hence of generating more steam for a given heat absorbing surface.

In each instance, the terminal portions of the curved or bowed tubes in the groups 22 and 22 are bent to provide the desiredradial entrances into their respective drums. The groups 22 and are so constructed and arranged with respect to each other and to the groups 2| as .to provide spaces 25 and- 26 between adjacent-groups, the purpose of these spaces is to permit the installation'of soot blowers, indicated at 21, which provide for'the quick and effective cleaning of the highly compact boilerdisclosed. Bafiies. 29 serve to :equalize the gas flow, particularly through the loosely'spaced rear groups 23 of tubes.

In order to provide for the maximum heat absorbing surface for a given weight of boiler, all of the-tubes with the exception of those tubes which are immediately adjacent and! delineate the upper portions of the combustion chamber are relatively small in diameter, the latter being relatively large in diameter, as will be presently explained. High efiiciency is essential in the interest of reduction of weight of fuel that'must be carried by the shipxas well as cost of operation. High efficiency meansa large fraction of the heat of the fuel absorbed by the water'in the tubes within an allowable limit ofdraft loss or gas-fiow resistance across thetube bank imposed I 'As stated above. those tubes of .by the capacity. High efiiciency is promoted in the construction described by the provision of a large number of small diameter tubes across the sets and by the provision of the maximum length of tubes so as to give a large heat absorbing surface.

the groups 2| which delineate or fiank'the combustion chamber are of larger diameter than the remaining tubes. The relatively larger tubes are indicated by the reference numeral 28 and in the construction illustrated comprise the I first tworows of tubes considered in the direction of gas fiow. The tubes 28 are made relatively larger so as to assure presence of water at all times in that portion of the boiler which is exposed directly to the radiant heatof combustion and, at the same time, so as toprovide the necessary supporting strength for the upper steam and water drum.v

It is essential that all of the tubes be protected against overheating which will result if the tubes develop dry spots, because such overheating will soften the metal and cause the tubes to burst. This is particularly true of the straight tubes in the groups 2|, including the tubes 28, as overheating will also impair their strength necessary to support the drum l2. The tubes are protected from overheating ,by the water therein; but the generation of steam reduces the water content toward the top and tends to produce dry spots, and this tendency varies inversely with the diameter. of the tube for a given length and directly with the degree to which the tube is heated. It is, therefore, apparent that by forming the tubes 28, which are in the hottest part of the furnace,

relatively large, the tendency to produce dry spots therein is exceedingly small and their usefulness as supports is not impaired. The remaining tubes may be made smaller in the interest of a large area of heat absorbing surface without danger of overheating, as the large tubes 2| protect the smaller tubes from the radiant heat of combustion.

' In the modified form of my invention shown in Fig. 3, the same desirable features of construction are present as are present in Figs. 1 and 2.

In Fig. 3, however, I have shown a superheater 30 arranged within a space 3| provided between groups Zia and 22a of one of the sets of tubes l5a. The space Si is provided by the arrange- -ment of the tubes in the groups 2la and 22a and by omitting certain of these tubes: The superheater 30 is of the return bend tube type and ,is supported by plate members 32 carried by.

brackets "which are in turn secured to large, approximately straight tubes 34 (only one shown) connecting the. water drum Ma with the upper steam-and water drum l2a.

While I have shown my invention in only two forms, it will be obvious to those skilled in the art that it is not so limited but is susceptibleof various other changes and modifications without departing from the spirit thereof, and .I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims. 7

I claim: 1

1. A water tube-boiler comprising, in combination, means defining a combustion chamber for a furnace, a steam and water drum arranged at the upper part of the furnace and above the combustion chamber, a pair of lower water drums arranged adjacent and delineating the upper portions of the combustion chamber and the second groups being disposed remote from the combustion chamber and in the rear of the first groups with spaces provided therebetween, the tubes forming the firstgroups being formed straight for practically their entire length; the tubes forming the second groups being similarly bowed away from the combustion chamber so as to permit expansion and contraction thereof incident to temperature changes,.a superheater disposed within the space between one of the second groups and the adjacent first group forming a set, each set of steam generating tubes constituting a single pass section with the furnace gases moving in a single direction from front to rear across the section and the tubes of said first groups being of materially larger diameter than the tubes of the remaining groups whereby the tubes of the first groups constitute the main support for the steam and water drum while the tubes of the other groups provide a predominating part of the entire steam generating surface, a gas outlet on each side of the drum, and gas distribution bailles each starting at an intermediate portion of one of said outlets and extending part way down over the rear tubes.

2. A boiler comprising in combination, means defining a combustion chamber of a furnace, a steam. and water drum arranged at the upper part of the furnace and above the combustion chamber, a pair of lower water drums disposed at opposite sides of the combustion chamber, sets of steam generating tubes connecting each lower water drum with the upper drum, each set being divided into first, second and third groups with the first groups being arranged adjacent and delineating the upper portions of the combustion chamber and the second and third groups arranged at the rear of the first groups in the order named, tubes forming the first groups being formed straight for practically their entire length, the tubes forming the second and third groups being bowed away from the combustion chamber so as to provide spaces between the first and second groups and the second and third groups and so as to permit expansion and contraction incident to temperature changes, soot blowers disposed in the spaces between the first and second groups, and the second and third groups, each set of steam generating tubes constituting a single pass section with the furnace gases moving in a single direction from front to rear across the section and the tubes of said first groups being of materially larger diameter than the tubes of the remaining groups whereby the tubes of the first groups constitute the main support for the steam and water drum while the tubes of the other groups provide a predominating part of the entire steam generating surface, a furnace gas outlet on each side of said drum, and gas distribution-baflles each starting at an intermediate portion of an outlet and extending part way down over the rear bowed tubes,

3. In a three-drum marine boiler, two submerged drums, an upper steam and water drum, a furnace, upwardly converging banks of steam generating tubes connecting the upper drum with the lower drums and arranged on opposite 20 sides of the furnace, the furnace gases being directed across each of said banks in a single pass, the tubes of said banks adjacent the furnace of large diameter and being substantially straight throughout the major portions of their lengths,

while the remaining tubes of the banks rearwardly of the straight tubes are of materially smaller diameter and are curved throughout their entire lengths, a gas outlet on each side of the,

drum, and gas distribution baflies each starting at an intermediate portion of a gas outlet and extending part way down over the rear tubes.

WILLIAM M. FIRSIHNG. 

